provider DNS response slow after DHCP IP renewal

Hello. I have a networking issue. Sometimes, because I am switching from one comupter to another to connect to the net, my provider doesn't assign my IP address through DHCP. I go to the other computer (Windows), release the IP and restart the network on mine (SuSE8.2). I do get an IP address but the DNS is then VERY slow to respond. I think that a reboot solves this issue each time but I presume that it means there is another way to solve it. Any hint knowing that I don't have the possibility to build/buy a router? TIA! Patrick